从控制器中的视图传递值

Question

I am passing a value from view(entered by user) to controller method which in turn fetches data from DB. Below is the code in my view

<%= form_tag({:controller=>"billings", :action=>"tablebill"}, method: :get) do %>
  <div class="center-data">Table Number:
    <div class="tinput"> <%= text_field_tag(:tableno) %></div>
  </div>
  <div class="ebutton">
    <%= submit_tag "Enter" %>
  </div>
<% end %>

Value tableno is what I need in my controller method and is coded as below

def tablebill
  @orders = List
   .select("itemname,tableno,quantity,amount")
   .where(:tableno => params[:tableno]).to_a

  @orders.each do |order|
    @totamount = @totamount + order.amount
  end

  @tax = @totamount/5
  @finalamount = @totamount + @tax

  respond_to do |format|
    format.html # tablebill.html.erb
  end  
end

The value is being passed successfully in the query but its returning nil. Below is the snippet from my server

Started GET "/billings/tablebill?utf8=%E2%9C%93&tableno=08&commit=Enter" for 127
.0.0.1 at 2013-09-05 15:50:01 +0530
  Processing by BillingsController#tablebill as HTML
  Parameters: {"utf8"=>"√", "tableno"=>"08", "commit"=>"Enter"}
  List Load (1.0ms)  SELECT itemname,tableno,quantity,amount FROM `lists` WHERE
`lists`.`tableno` = '08'
Completed 500 Internal Server Error in 230ms

NoMethodError (You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.+):
  app/controllers/billings_controller.rb:8:in `block in tablebill'
  app/controllers/billings_controller.rb:7:in `each'
  app/controllers/billings_controller.rb:7:in `tablebill'

Problem is when I execute same query on rails console, its giving results. Below is snippet from rails console

irb(main):073:0> @orders = List.select("itemname,tableno,quantity,amount").where(:tableno => '08')
=> [#<List tableno: "08", itemname: "test81 ", quantity: "1", amount: "
3.25">, #<List tableno: "08", itemname: "Test82", quantity: "1", amou
nt: "3.75">, #<List tableno: "08", itemname: "Test83", quantity: "1
", amount: "3.75">]

I have tried a lot with almost all values present in DB but every time its same when done through view and I get results when executing query through rails console. I have tried a lot before posting here as i don't think any issue in passing the value. Its just that the select query isn't working. Please advise. Thanks.

Answer 1

I don't think it's because params[:tableno] is nil I think it is because you haven't initialized @totamount . Then when you try to add the first order.amount to it you are getting an error because you can't add to nil .

Try either setting @totamount = 0 before your loop or doing:

@totamount = order.map(&:amount).inject(&:+)

To add all the amounts together.